1. Field of the Invention
This invention relates to a carbon nanotube, more particularly to an iridium-doped carbon nanotube and an electrode and a sensor including the iridium doped carbon nanotube.
2. Description of the Related Art
Carbon nanotubes (CNTs) have been widely adopted into a variety of composite materials, transistors, or sensors because of their physical properties such as light weight, superior corrosion resistance, high hardness, high melting points, as well as high electrical conductivity. For instance, Taiwanese Patent No. I276799 discloses a biosensor including an electrode which has a modified carbon nanotubes layer thereon for enhancing the sensitivity of detecting specific biological molecules.
In Anal. Chem., 2003, 75, 2075-2079, J. Wang et al. disclose an electrochemical sensor including a carbon nanotubes/Teflon composite material, which can be further modified to be a biosensor by immobilizing enzymes on a sensing area of the electrochemical sensor. However, the aforesaid carbon nanotube/Teflon composite biosensor lacks a metal dopant and thus has inferior sensitivity. L. Fang et al. disclose an electrochemical biosensor for detecting β-nicotinamide adenine dinucleotide (NADH) in Sens. Actuators B, 2008, 129, 818-825, including a modified carbon/iridium working electrode that is doped with 5% of iridium particles to enhance the sensitivity of the electrochemical biosensor. However, high amounts of metal particles doped in the working electrode result in a lower signal-to-noise ratio so that the selectivity of the working electrode is not sufficiently high.
Therefore, there is a need in the art to provide a composite material to modify an electrode for having high sensitivity and yet maintaining sufficiently high selectivity.